1. Field
The present embodiments relate to a support for a radiation therapy system.
2. Related Art
Radiation systems are used in medical therapy for irradiating diseased tissue, for example, tumor tissue. Suitable radiation types of therapy include, for example, high-energy X-radiation in the megavolt range; lightweight particle radiation (i.e. electrons or positrons or protons); and heavy particle radiation (i.e. oxygen or carbon ions). Because of the radiation, the bonds of the living tissue are destroyed or atoms are ionized. These alterations can cause destruction or death of the tissue. Although this effect is intended with regard to the tumor tissue or diseased tissue, this effect must be avoided in healthy tissue. In a desired radiation system, the radiation dose administered to diseased tissue should be increased and the radiation dose administered to the healthy tissue should be reduced.
Generally, the placement of the radiation dose with regard to the penetration depth into the irradiated tissue is achieved by a suitable choice of both the type and the energy of the radiation. The two-dimensional, lateral localization of the radiation in terms of the radiation direction is achieved by the circumference of the beam and by its contour. Sharp focusing allows coarse localization by diaphragms, and contoured localization by collimators, for example, multi-leaf collimators, which allow many different contours. When irradiating an organ, for example, it is possible to shape the beam of rays so that the beam corresponds substantially to the contour of the organ. Accordingly, only a minimum amount of tissue located around the organ is irradiated.
The contour of the beam is monitored both continuously and in each individual case. The monitoring increases the operating safety and avoids risk of the patient being exposed to unnecessarily high radiation exposure caused by radiation not accurately aimed at the desired organ. To help control the monitoring, visible light can, for example, pass through the beam shaping device, or in other words the focusing, diaphragms and collimators. The visible light makes optical control possible. The radiation type must have the same optical properties as visible light. Detector elements, for example, X-ray image detectors, are used at the position where a patient is to be irradiated. For example, in the case of X-radiation, a control image of the beam is obtained from the detector element.
To properly prepare for the irradiation, both an exact establishment of the contour of the beam and an equally exact positioning of the patient to be irradiated are necessary. The three-dimensional position of the patient's tissue to be irradiated is determined with the greatest possible accuracy. This three-dimensional position is placed as precisely as possible in the active center or isocenter of the radiation system. Only the exact positioning at the isocenter assures that the contour of the beam is precisely congruent with the contour of the tissue to be irradiated. The position of the tissue to be treated is determined by a diagnostic system, which need not be identical with the therapy system. The positioning of the tissue, which takes place after determining the three-dimensional position, involves major possibilities of error, which can be a hindrance to exact positioning.
To avoid the possibility of error, a diagnostic and therapy system are combined. In this combined system, a patient is first diagnosed and then treated in the same position. Inaccuracies from an intervening repositioning of the patient and from an intervening positioning of the therapy system are avoided. The three-dimensional orientation of the therapy component of the system to the diagnostic component is fixed and increases the positioning accuracy of the equipment.
When disposing the therapy component relative to the diagnostic component, a distinction is made between two possible configurations. First, the beam path of the diagnostic system can differ three-dimensionally from the beam of the therapy system. For example, the diagnostic radiation extends perpendicular to the therapeutic radiation. For example, if the patient is treated with a vertical beam path, then the diagnostic beam path is horizontal. The different three-dimensional course does involve inaccuracies, because only different three-dimensional coordinates are able to be determined. In this example, the horizontal diagnostic radiation is suitable for determining the vertical three-dimensional coordinate of the tissue. The horizontal three-dimensional coordinates are determined by the contouring of the therapeutic beam of rays. Alternatively, the various equipment components are spaced apart from one another three-dimensionally without interfering with one another.
U.S. Pat. No. 6,888,919 discloses a radiotherapy system, which has therapy components disposed in a first gantry. The diagnostic components are disposed in a second gantry. The gantries are movable independently of one another and allow various beam path configurations to be established. Each gantry requires its own free space for motion and includes mechanical components that are located around the patient in the immediate vicinity of the therapy area.
Second, a constellation is selected in which the axis of the diagnostic beam path coincides three-dimensionally with that of the therapeutic beam path. The diagnosis and therapy have the same optical geometry, which increases the accuracy. The various equipment components are disposed in the same beam path and may interfere with one another. The space available for installation is reduced and the components are integrated into the diagnostic and/or therapy system. The components are adapted to one another in a space-saving way.
In an example, an X-radiation therapy system, a high-energy X-radiation source, a less high-energy further X-radiation source, and at least one X-ray image detector in the less high-energy region are disposed in the same beam path. In addition, an X-radiation detector in the high-energy area is used. Both the patient and the therapist should have as much space available as possible, so as not to excessively limit the treatment options and patient comfort.
Austrian Patent Disclosure AT 156705 B discloses a device for X-ray production of images of slices or layers of the body, or of both slices and layers of the body. The X-ray tube and the holder for the image-collecting layer (cassette holder) are pivotable about an axis located in the plane of the body section to be imaged. The X-ray tube and holder are pivotable by the disposition of a double lever on both arms. The X-ray that passes through any point of the body section to be imaged always strikes the same point of the image layer, which is kept parallel to the section plane in the pivoting motion.